In the manufacturing of corrugated sheet material for stacked plate heat exchangers of the type disclosed in U.S. Pat. No. 3,759,323 issued on Sept. 18, 1973 to H. J. Dawson, et al, and assigned to the assignee of the present invention, problems have been experienced in obtaining deeply drawn corrugations and high quality transition zones intermediate the centrally disposed corrugations and the marginal flat portions of the sheets. This is largely due to the fact that the total surface area provided by the sides or walls of the grooves of the corrugations determines the heat exchanger's capacity and effectiveness, and to meet this requirement and to simultaneously limit the total number of required sheets both the corrugation height and the number of corrugations per unit width have been substantially increased. Consequently, during formation of the corrugations from flat sheet material, the sheets tear because the ductility limits of the material have been exceeded.
More specifically, when high temperature corrosion and heat resistant alloy metal sheets of from 2 to 8 mils thickness are formed into the aforementioned corrugate heat exchanger sheets by striking them in dies the corrugation height is limited to less than about 1 mm (0.039"). When corrugated heat transfer heights greater than this are stamped, sheet splitting occurs as a result of exceeding the maximum allowable ductility limit of the alloy. Of course, multiple and progressive die stamping stages are possible with heat treatment between the stages in order to relieve the stresses generated during each stamping operation, but this would be a very costly process.